The imaging of body volumes and internal parts of a live subject is practiced notably in the field of medical diagnostics and therapy, that is, in the context of X-ray fluoroscopy. Therefore, the X-ray projection of a biological body volume will be considered hereinafter by way of example, but the present invention is not intended to be restricted thereto and can be used in all fields of application with similar conditions.
An angiogram is usually produced in order to diagnose and treat diseases of a patient's vascular system. An angiogram is a two-dimensional or three-dimensional image which shows the vascular tree or part thereof either on its own or emphasized with respect to the background. Angiograms are typically produced by means of an X-ray apparatus and with injection of an X-ray contrast agent.
Recent developments in particular of the mechanical framework of C-arm systems have improved the mechanical precision of X-ray scanning systems being attached to a C-arm such that 3D reconstructions of an object under examination have become possible. The X-ray scanning system comprises an X-ray source and an X-ray detector being arranged vis-à-vis with respect to each other. A 3D reconstruction may be based exclusively on a variety of 2D X-ray projection images obtained with the X-ray scanning system while moving around the object under examination in a rotational manner.
WO 2004/093683 discloses an apparatus and a method for a joint 3D display of an angiogram of a vascular system and local intravascular images. The angiogram is recorded by means of an X-ray apparatus, while the local intravascular images are generated by an ultrasound probe on a catheter. The position of the probe is determined by a position determination unit and is used to assign the recorded volume to the angiogram. The angiogram and the local intravascular image may be displayed in an overlapping manner in the same image. A physician can therefore link the information from the local intravascular image and from the angiogram at a glance and in a particularly intuitive manner.
U.S. Pat. No. 4,777,956 discloses a NMR angiography system, which is adapted to combine the isolated vessel image with a projection image of the anatomy. For example, the vessels can be displayed as a color overlay on a black and white anatomical image.
WO 03/077202 A1 discloses techniques for combining various types of diagnostic images to allow a user to view more useful information. In one embodiment, a composite image is obtained by fusing multi-planar reformat and maximum intensity projection images or minimum intensity projection images obtained from a CT scan. The maximum intensity projection image is obtained from a positron emission tomography scan. The resulting superimposed images can help a physician to see the diagnostic information in context.
There may be a need for providing an improved visualization of 3D images of an object under examination.